This invention relates to fluid operating apparatus for positioning of load devices such as industrial and commercial doors and in particular to a pneumatic operating apparatus having switching means for selectively reversing the driving and holding position of a pneumatic motor means.
Fluid driven positioning apparatus is widely employed in industry for rapidly and reliably positioning of various types of loads, including valves, dampers, machine operating elements as well as various closure members. In the institutional and commercial field, automatic door closures may employ fluid driven operators for automatic closing and opening of the doors in response to an appropriate input signal. Pneumatic driven door operators may employ air supplies which are generally available in other parts of the institution or which can be readily supplied. Pneumatic systems also are highly desirable in connection with the convenient method of exhausting of the system to the atmosphere.
A particularly satisfactory pneumatic door operator providing accurate and versatile controlled movement of the door to permit safe movement of personnel and associated equipment is shown in Applicant's co-pending application, entitled "FLUID ACTIVATED LOAD OPERATOR" and filed herewith. In the preferred embodiment of that application a power cylinder unit includes unique metering valve units connected to each end of the power cylinder for selective connection to an exhaust means and to a pressure source. The metering valve units include a one-way passageway to supply air and a pair of parallel passageways providing for a controlled exhaust to regulate the acceleration and deceleration of the drive. A solenoid control valve selectively establishes the opposite connections to the metering valve units and thereby to the power cylinder unit for selectively opening and closing of the door.
An adaptive interconnecting mechanical linkage includes a drive arm connected to an adjustable excursion arm or link which, in turn, is pivotally interconnected to a second positioning link or arm. A pivotal mounting bracket is adjustably secured to the outer end of the positioning arm for attachment to the door. The mechanical linkage permits the ready adaptation of the single power operator for various type of doors.
The control of the valve or other control means is conveniently automated by an electrical control system which has an electroresponsive means to properly set the control means. The electrical control system is generally provided with suitable electrical switches for actuating of the electroresponsive means in response to suitable manual switch operation. In automatic door operators, safety devices should be incorporated to prevent damage to persons and objects moving through the opening as well as to the door and operator as such. Continued and reliable control operation is particularly required in industrial and commercial applications where relatively heavy doors are encountered in varying environmental conditions. Thus, the motor means and switch means should respond to rapidly and reliably reverse the door movement, particularly during the door closing when personnel and/or equipment may be within the door opening.